147 / 2022-03-14 11:04:21

Fault Location Method based on Leakage Current Characteristic of XLPE Cable

Double end grounding, leakage current, fault location, on-line detection

Fault Location Method based on Leakage Current Characteristic of XLPE Cable

 Ju KONG，Shusheng ZHENG，Xiaohu YAN, Yan ZHAO

State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources (North China Electric Power University)

Kongju0308@163.com



Purpose/Aim

The main problem of existing cable fault location methods is that online measurement cannot be realized. Therefore, considering the metal sheath structure of power cables, a cable fault location method based on leakage current characteristic is proposed.

Experimental/Modeling methods

The grounding current at both ends of the cable under fault includes induced circulation, capacitive current and leakage current. According to the harmonic analysis method of resistive current extraction, the current component that is consistent with the phase of cable core voltage can be extracted. In this paper, the fault point voltage is replaced by the terminal voltage of the cable core, and the induced circulation in the grounding current of the two ends of the cable without fault is obtained by harmonic analysis. When the cable has a low resistance or high resistance fault, the leakage current flowing through the fault point is in the same phase with the cable core voltage at the fault point. The harmonic analysis method is used to analyze the grounding current and exclude the inductive circulating current component, so as to obtain the characteristic quantity of leakage current. Combined with the metal shield resistance and grounding resistance of the cable, the fault distance is calculated. ATP-EMTP is used to model 10 kV XLPE cable with a distance of 1 km. The resistance values of 500 Ω and 5000 Ω are set at the main insulation of different locations to simulate low resistance and high resistance faults, which shows the effectiveness of the method.

Results/discussion

In the case of low resistance and high resistance, the fault distance is set to 200 m, 350 m and 600 m from the cable head. Through the calculation and analysis of the simulation results, the ranging error can be controlled within 6 %.

Conclusions

The method proposed in this paper can provide a new idea for online fault location of cables, but this method also has some limitations, such as that the inductance component is not considered in the model construction. This method has room for further optimization.